This invention relates to a method of manufacturing a door for a motorcar in which a door inner member is assembled by combining accessory parts such as a sash or the like to an inner panel, a beam is combined to the door inner member and then the door inner member is assembled to an outer panel, as well as to an apparatus to be used for carrying out the above method.
As an apparatus for manufacturing a door for a motorcar, there is conventionally known one which comprises, in the order from a starting end of the working line, a fitting station for a door inner member, a combining station for combining a beam and an assembling station for assembling the door inner member and an outer panel. In this apparatus, the door inner member is assembled by welding together an inner panel and accessory parts such as a sash, a hinge side member or the like which are set in position on a welding jig which is provided in the fitting station by welding guns which are provided in the welding jig. Then, the door inner member is transferred by a transfer apparatus to a welding jig which is provided in the beam combining station. The beam is set to this door inner member and is welded thereto by welding guns which are provided in the welding jig. Thereafter, the door inner member is transferred to a jig which is provided in the assembling station to assemble the outer panel to the door inner member. Then, hemming and welding of the hemmed portion are carried out (see Japanese Published Examined Patent Application No. 3467/1982).
In the above-described apparatus, each of the jigs are specially prepared for each type of door and, therefore, a plural kinds of jigs must be prepared to cope with the change in the type of door. In order to complete the assembling of the door inner member in the fitting station like in the above-described conventional apparatus, a large number of welding guns must be mounted on the welding jig to be provided in the fitting station. The costs for such many welding guns become expensive and therefore it is not advantageous from economical point of view to prepare so many expensive welding jigs.
If the number of welding guns to be mounted on the welding jig is reduced, only tack-welding of the door inner member is carried out in the fitting station and reinforcing-welding of the door inner member is carried out by welding robots in the next station, the overall costs of the equipment can be reduced because the exchanging of the welding robots is not necessary.
However, in such an arrangement, since a reinforcing welding station as the above-described next station is added between the fitting station and the beam combining station, the length of the working line becomes longer. Further, since the welding jig to be provided in the beam combining station becomes expensive, a drastic reduction in the equipment costs cannot be expected.